Does NOR chip drivers support PPB protection

[Gernot Hoyler]

> So if we are willing to use the freeze bit that we need some callback
> into the chip specific driver (mapping driver) that can issue a reset.
> Comments? 

Normally, the purpose of the PPB lock bit is to prevent users from
changing the PPB bits/settings after initial setup. In this case, you
program your image to flash and lock certain sectors (e.g. on a tester
or factory in-system programming). Afterwards you set the PPB lock bit
pretty early in the boot phase (e.g. boot loader or boot code) to
protect both the sectors and their PPB bits.